Add distanceStrategy parameter

Author: JJK801

packages/components/nodes/vectorstores/Postgres/Postgres.ts

@@ -136,6 +136,29 @@ class Postgres_VectorStores implements INode {
                 additionalParams: true,
                 optional: true
             },
+            {
+                label: 'Distance Strategy',
+                name: 'distanceStrategy',
+                description: 'Strategy  for calculating distances between vectors',
+                type: 'option',
+                options: [
+                    {
+                        label: 'Cosine',
+                        name: 'cosine'
+                    },
+                    {
+                        label: 'Euclidean',
+                        name: 'euclidean'
+                    },
+                    {
+                        label: 'Inner Product',
+                        name: 'innerProduct'
+                    }
+                ],
+                additionalParams: true,
+                default: 'cosine',
+                optional: true
+            },
             {
                 label: 'Postgres Metadata Filter',
                 name: 'pgMetadataFilter',

packages/components/nodes/vectorstores/Postgres/driver/PGVector.ts

@@ -1,6 +1,6 @@
 import { VectorStoreDriver } from './Base'
 import { getCredentialData, getCredentialParam } from '../../../../src'
-import { PGVectorStore, PGVectorStoreArgs } from '@langchain/community/vectorstores/pgvector'
+import { DistanceStrategy, PGVectorStore, PGVectorStoreArgs } from '@langchain/community/vectorstores/pgvector'
 import { Document } from '@langchain/core/documents'
 import { PoolConfig } from 'pg'
 
@@ -45,7 +45,8 @@ export class PGVectorDriver extends VectorStoreDriver {
             tableName: this.getTableName(),
             columns: {
                 contentColumnName: (this.nodeData.inputs?.contentColumnName || PGVectorDriver.CONTENT_COLUMN_NAME_DEFAULT) as string
-            }
+            },
+            distanceStrategy: (this.nodeData.inputs?.distanceStrategy || 'cosine') as DistanceStrategy
         }
     }
 

packages/components/nodes/vectorstores/Postgres/driver/TypeORM.ts

@@ -80,7 +80,8 @@ export class TypeORMDriver extends VectorStoreDriver {
                 k,
                 tableName,
                 await this.getPostgresConnectionOptions(),
-                filter ?? metadataFilters
+                filter ?? metadataFilters,
+                this.computedOperatorString
             )
         }
 
@@ -105,12 +106,28 @@ export class TypeORMDriver extends VectorStoreDriver {
         return instance
     }
 
+    get computedOperatorString() {
+        const { distanceStrategy = 'cosine' } = this.nodeData.inputs || {}
+
+        switch (distanceStrategy) {
+            case 'cosine':
+                return '<=>'
+            case 'innerProduct':
+                return '<#>'
+            case 'euclidean':
+                return '<->'
+            default:
+                throw new Error(`Unknown distance strategy: ${distanceStrategy}`)
+        }
+    }
+
     static similaritySearchVectorWithScore = async (
         query: number[],
         k: number,
         tableName: string,
         postgresConnectionOptions: ICommonObject,
-        filter?: any
+        filter?: any,
+        distanceOperator: string = '<=>'
     ) => {
         const embeddingString = `[${query.join(',')}]`
         let notExists = ''
@@ -127,7 +144,7 @@ export class TypeORMDriver extends VectorStoreDriver {
         }
 
         const queryString = `
-            SELECT *, embedding <=> $1 as "_distance"
+            SELECT *, embedding ${distanceOperator} $1 as "_distance"
             FROM ${tableName}
             WHERE metadata @> $2
             ${notExists}